Association of global sagittal deformity with functional disability two years after total hip arthroplasty

Abstract

Introduction: The relationship between spinopelvic alignment and functional disability after total hip arthroplasty (THA) has not been fully elucidated despite the growing recognition of its importance on patient-reported outcome measures. We aimed to determine whether global sagittal deformity was associated with post-operative disability.Materials and methods: This prospective analysis was based on 208 THAs that were followed up for 2 years. The Hip Disability and Osteoarthritis Outcome Score-Joint Replacement (HOOS-JR) ranging from a scale of 0 (complete joint disability) to 100 (perfect joint health) was utilised to divide eligible patients into two groups with and without disability, using 70 as the threshold. Multivariate analysis was performed to evaluate the factors associated with disability. To identify the cut-off value of the parameters for predicting disability (HOOS-JR <70/100), we used the receiver-operating characteristic curve.Results: The disability (30 hips) and control (178 hips) groups showed a significant difference in body height (p = 0.020), pre-operative T1 pelvic angle divided by pelvic incidence (T1PA/PI) (p = 0.018), pelvic incidence minus lumbar lordosis (p = 0.027), post-operative HOOS-JR (p = 0.010), and satisfaction (p = 0.033). On multivariate analysis, the following factors were associated with persistent disability: T1PA/PI >0.2 (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.19–4.14; p < 0.001) and height <148 cm (OR, 1.26; 95% CI, 1.09–1.48; p = 0.011). The cut-off value of pre-operative T1PA/PI was >0.19 with a sensitivity of 95% and specificity of 85%. Post-operative satisfaction (p < 0.001) and HOOS-JR (p = 0.023) differed between the two groups when the pre-operative cut-off value was chosen as 0.2.Conclusions: A T1PA/PI >0.2 was associated with greater disability after THA. Clinicians should be aware that patient-related factors, including global spinal deformities, particularly in patients with a short stature, can influence THA outcomes at 2 years postoperatively.